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sshd.c
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sshd.c
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/* $OpenBSD: sshd.c,v 1.478 2016/11/30 00:28:31 dtucker Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* This program is the ssh daemon. It listens for connections from clients,
* and performs authentication, executes use commands or shell, and forwards
* information to/from the application to the user client over an encrypted
* connection. This can also handle forwarding of X11, TCP/IP, and
* authentication agent connections.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* SSH2 implementation:
* Privilege Separation:
*
* Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
* Copyright (c) 2002 Niels Provos. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include "openbsd-compat/sys-tree.h"
#include "openbsd-compat/sys-queue.h"
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#include <grp.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#ifdef WITH_OPENSSL
#include <openssl/dh.h>
#include <openssl/bn.h>
#include <openssl/rand.h>
#include "openbsd-compat/openssl-compat.h"
#endif
#ifdef HAVE_SECUREWARE
#include <sys/security.h>
#include <prot.h>
#endif
#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "rsa.h"
#include "sshpty.h"
#include "packet.h"
#include "log.h"
#include "buffer.h"
#include "misc.h"
#include "match.h"
#include "servconf.h"
#include "uidswap.h"
#include "compat.h"
#include "cipher.h"
#include "digest.h"
#include "key.h"
#include "kex.h"
#include "myproposal.h"
#include "authfile.h"
#include "pathnames.h"
#include "atomicio.h"
#include "canohost.h"
#include "hostfile.h"
#include "auth.h"
#include "authfd.h"
#include "msg.h"
#include "dispatch.h"
#include "channels.h"
#include "session.h"
#include "monitor.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "ssh-sandbox.h"
#include "version.h"
#include "ssherr.h"
/* Re-exec fds */
#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
extern char *__progname;
/* Server configuration options. */
ServerOptions options;
/* Name of the server configuration file. */
char *config_file_name = _PATH_SERVER_CONFIG_FILE;
/*
* Debug mode flag. This can be set on the command line. If debug
* mode is enabled, extra debugging output will be sent to the system
* log, the daemon will not go to background, and will exit after processing
* the first connection.
*/
int debug_flag = 0;
/* Flag indicating that the daemon should only test the configuration and keys. */
int test_flag = 0;
/* Flag indicating that the daemon is being started from inetd. */
int inetd_flag = 0;
/* Flag indicating that sshd should not detach and become a daemon. */
int no_daemon_flag = 0;
/* debug goes to stderr unless inetd_flag is set */
int log_stderr = 0;
/* Saved arguments to main(). */
char **saved_argv;
int saved_argc;
/* re-exec */
int rexeced_flag = 0;
int rexec_flag = 1;
int rexec_argc = 0;
char **rexec_argv;
/*
* The sockets that the server is listening; this is used in the SIGHUP
* signal handler.
*/
#define MAX_LISTEN_SOCKS 16
int listen_socks[MAX_LISTEN_SOCKS];
int num_listen_socks = 0;
/*
* the client's version string, passed by sshd2 in compat mode. if != NULL,
* sshd will skip the version-number exchange
*/
char *client_version_string = NULL;
char *server_version_string = NULL;
/* Daemon's agent connection */
int auth_sock = -1;
int have_agent = 0;
/*
* Any really sensitive data in the application is contained in this
* structure. The idea is that this structure could be locked into memory so
* that the pages do not get written into swap. However, there are some
* problems. The private key contains BIGNUMs, and we do not (in principle)
* have access to the internals of them, and locking just the structure is
* not very useful. Currently, memory locking is not implemented.
*/
struct {
Key **host_keys; /* all private host keys */
Key **host_pubkeys; /* all public host keys */
Key **host_certificates; /* all public host certificates */
int have_ssh2_key;
} sensitive_data;
/* This is set to true when a signal is received. */
static volatile sig_atomic_t received_sighup = 0;
static volatile sig_atomic_t received_sigterm = 0;
/* session identifier, used by RSA-auth */
u_char session_id[16];
/* same for ssh2 */
u_char *session_id2 = NULL;
u_int session_id2_len = 0;
/* record remote hostname or ip */
u_int utmp_len = HOST_NAME_MAX+1;
/* options.max_startup sized array of fd ints */
int *startup_pipes = NULL;
int startup_pipe; /* in child */
/* variables used for privilege separation */
int use_privsep = -1;
struct monitor *pmonitor = NULL;
int privsep_is_preauth = 1;
/* global authentication context */
Authctxt *the_authctxt = NULL;
/* sshd_config buffer */
Buffer cfg;
/* message to be displayed after login */
Buffer loginmsg;
/* Unprivileged user */
struct passwd *privsep_pw = NULL;
/* Prototypes for various functions defined later in this file. */
void destroy_sensitive_data(void);
void demote_sensitive_data(void);
static void do_ssh2_kex(void);
/*
* Close all listening sockets
*/
static void
close_listen_socks(void)
{
int i;
for (i = 0; i < num_listen_socks; i++)
close(listen_socks[i]);
num_listen_socks = -1;
}
static void
close_startup_pipes(void)
{
int i;
if (startup_pipes)
for (i = 0; i < options.max_startups; i++)
if (startup_pipes[i] != -1)
close(startup_pipes[i]);
}
/*
* Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
* the effect is to reread the configuration file (and to regenerate
* the server key).
*/
/*ARGSUSED*/
static void
sighup_handler(int sig)
{
int save_errno = errno;
received_sighup = 1;
signal(SIGHUP, sighup_handler);
errno = save_errno;
}
/*
* Called from the main program after receiving SIGHUP.
* Restarts the server.
*/
static void
sighup_restart(void)
{
logit("Received SIGHUP; restarting.");
platform_pre_restart();
close_listen_socks();
close_startup_pipes();
alarm(0); /* alarm timer persists across exec */
signal(SIGHUP, SIG_IGN); /* will be restored after exec */
execv(saved_argv[0], saved_argv);
logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
strerror(errno));
exit(1);
}
/*
* Generic signal handler for terminating signals in the master daemon.
*/
/*ARGSUSED*/
static void
sigterm_handler(int sig)
{
received_sigterm = sig;
}
/*
* SIGCHLD handler. This is called whenever a child dies. This will then
* reap any zombies left by exited children.
*/
/*ARGSUSED*/
static void
main_sigchld_handler(int sig)
{
int save_errno = errno;
pid_t pid;
int status;
while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
(pid < 0 && errno == EINTR))
;
signal(SIGCHLD, main_sigchld_handler);
errno = save_errno;
}
/*
* Signal handler for the alarm after the login grace period has expired.
*/
/*ARGSUSED*/
static void
grace_alarm_handler(int sig)
{
if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
kill(pmonitor->m_pid, SIGALRM);
/*
* Try to kill any processes that we have spawned, E.g. authorized
* keys command helpers.
*/
if (getpgid(0) == getpid()) {
signal(SIGTERM, SIG_IGN);
kill(0, SIGTERM);
}
/* Log error and exit. */
sigdie("Timeout before authentication for %s port %d",
ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
}
static void
sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
{
u_int i;
int remote_major, remote_minor;
char *s, *newline = "\n";
char buf[256]; /* Must not be larger than remote_version. */
char remote_version[256]; /* Must be at least as big as buf. */
xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s",
PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
*options.version_addendum == '\0' ? "" : " ",
options.version_addendum, newline);
/* Send our protocol version identification. */
if (atomicio(vwrite, sock_out, server_version_string,
strlen(server_version_string))
!= strlen(server_version_string)) {
logit("Could not write ident string to %s port %d",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
cleanup_exit(255);
}
/* Read other sides version identification. */
memset(buf, 0, sizeof(buf));
for (i = 0; i < sizeof(buf) - 1; i++) {
if (atomicio(read, sock_in, &buf[i], 1) != 1) {
logit("Did not receive identification string "
"from %s port %d",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
cleanup_exit(255);
}
if (buf[i] == '\r') {
buf[i] = 0;
/* Kludge for F-Secure Macintosh < 1.0.2 */
if (i == 12 &&
strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
break;
continue;
}
if (buf[i] == '\n') {
buf[i] = 0;
break;
}
}
buf[sizeof(buf) - 1] = 0;
client_version_string = xstrdup(buf);
/*
* Check that the versions match. In future this might accept
* several versions and set appropriate flags to handle them.
*/
if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
&remote_major, &remote_minor, remote_version) != 3) {
s = "Protocol mismatch.\n";
(void) atomicio(vwrite, sock_out, s, strlen(s));
logit("Bad protocol version identification '%.100s' "
"from %s port %d", client_version_string,
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
close(sock_in);
close(sock_out);
cleanup_exit(255);
}
debug("Client protocol version %d.%d; client software version %.100s",
remote_major, remote_minor, remote_version);
ssh->compat = compat_datafellows(remote_version);
if ((ssh->compat & SSH_BUG_PROBE) != 0) {
logit("probed from %s port %d with %s. Don't panic.",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
client_version_string);
cleanup_exit(255);
}
if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
logit("scanned from %s port %d with %s. Don't panic.",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
client_version_string);
cleanup_exit(255);
}
if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
logit("Client version \"%.100s\" uses unsafe RSA signature "
"scheme; disabling use of RSA keys", remote_version);
}
if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) {
fatal("Client version \"%.100s\" uses unsafe key agreement; "
"refusing connection", remote_version);
}
chop(server_version_string);
debug("Local version string %.200s", server_version_string);
if (remote_major == 2 ||
(remote_major == 1 && remote_minor == 99)) {
enable_compat20();
} else {
s = "Protocol major versions differ.\n";
(void) atomicio(vwrite, sock_out, s, strlen(s));
close(sock_in);
close(sock_out);
logit("Protocol major versions differ for %s port %d: "
"%.200s vs. %.200s",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
server_version_string, client_version_string);
cleanup_exit(255);
}
}
/* Destroy the host and server keys. They will no longer be needed. */
void
destroy_sensitive_data(void)
{
int i;
for (i = 0; i < options.num_host_key_files; i++) {
if (sensitive_data.host_keys[i]) {
key_free(sensitive_data.host_keys[i]);
sensitive_data.host_keys[i] = NULL;
}
if (sensitive_data.host_certificates[i]) {
key_free(sensitive_data.host_certificates[i]);
sensitive_data.host_certificates[i] = NULL;
}
}
}
/* Demote private to public keys for network child */
void
demote_sensitive_data(void)
{
Key *tmp;
int i;
for (i = 0; i < options.num_host_key_files; i++) {
if (sensitive_data.host_keys[i]) {
tmp = key_demote(sensitive_data.host_keys[i]);
key_free(sensitive_data.host_keys[i]);
sensitive_data.host_keys[i] = tmp;
}
/* Certs do not need demotion */
}
}
static void
reseed_prngs(void)
{
u_int32_t rnd[256];
#ifdef WITH_OPENSSL
RAND_poll();
#endif
arc4random_stir(); /* noop on recent arc4random() implementations */
arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
#ifdef WITH_OPENSSL
RAND_seed(rnd, sizeof(rnd));
/* give libcrypto a chance to notice the PID change */
if ((RAND_bytes((u_char *)rnd, 1)) != 1)
fatal("%s: RAND_bytes failed", __func__);
#endif
explicit_bzero(rnd, sizeof(rnd));
}
static void
privsep_preauth_child(void)
{
gid_t gidset[1];
/* Enable challenge-response authentication for privilege separation */
privsep_challenge_enable();
#ifdef GSSAPI
/* Cache supported mechanism OIDs for later use */
if (options.gss_authentication)
ssh_gssapi_prepare_supported_oids();
#endif
reseed_prngs();
/* Demote the private keys to public keys. */
demote_sensitive_data();
/* Demote the child */
if (getuid() == 0 || geteuid() == 0) {
/* Change our root directory */
if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
strerror(errno));
if (chdir("/") == -1)
fatal("chdir(\"/\"): %s", strerror(errno));
/* Drop our privileges */
debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
(u_int)privsep_pw->pw_gid);
gidset[0] = privsep_pw->pw_gid;
if (setgroups(1, gidset) < 0)
fatal("setgroups: %.100s", strerror(errno));
permanently_set_uid(privsep_pw);
}
}
static int
privsep_preauth(Authctxt *authctxt)
{
int status, r;
pid_t pid;
struct ssh_sandbox *box = NULL;
/* Set up unprivileged child process to deal with network data */
pmonitor = monitor_init();
/* Store a pointer to the kex for later rekeying */
pmonitor->m_pkex = &active_state->kex;
if (use_privsep == PRIVSEP_ON)
box = ssh_sandbox_init(pmonitor);
pid = fork();
if (pid == -1) {
fatal("fork of unprivileged child failed");
} else if (pid != 0) {
debug2("Network child is on pid %ld", (long)pid);
pmonitor->m_pid = pid;
if (have_agent) {
r = ssh_get_authentication_socket(&auth_sock);
if (r != 0) {
error("Could not get agent socket: %s",
ssh_err(r));
have_agent = 0;
}
}
if (box != NULL)
ssh_sandbox_parent_preauth(box, pid);
monitor_child_preauth(authctxt, pmonitor);
/* Wait for the child's exit status */
while (waitpid(pid, &status, 0) < 0) {
if (errno == EINTR)
continue;
pmonitor->m_pid = -1;
fatal("%s: waitpid: %s", __func__, strerror(errno));
}
privsep_is_preauth = 0;
pmonitor->m_pid = -1;
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) != 0)
fatal("%s: preauth child exited with status %d",
__func__, WEXITSTATUS(status));
} else if (WIFSIGNALED(status))
fatal("%s: preauth child terminated by signal %d",
__func__, WTERMSIG(status));
if (box != NULL)
ssh_sandbox_parent_finish(box);
return 1;
} else {
/* child */
close(pmonitor->m_sendfd);
close(pmonitor->m_log_recvfd);
/* Arrange for logging to be sent to the monitor */
set_log_handler(mm_log_handler, pmonitor);
privsep_preauth_child();
setproctitle("%s", "[net]");
if (box != NULL)
ssh_sandbox_child(box);
return 0;
}
}
static void
privsep_postauth(Authctxt *authctxt)
{
#ifdef DISABLE_FD_PASSING
if (1) {
#else
if (authctxt->pw->pw_uid == 0) {
#endif
/* File descriptor passing is broken or root login */
use_privsep = 0;
goto skip;
}
/* New socket pair */
monitor_reinit(pmonitor);
pmonitor->m_pid = fork();
if (pmonitor->m_pid == -1)
fatal("fork of unprivileged child failed");
else if (pmonitor->m_pid != 0) {
verbose("User child is on pid %ld", (long)pmonitor->m_pid);
buffer_clear(&loginmsg);
monitor_child_postauth(pmonitor);
/* NEVERREACHED */
exit(0);
}
/* child */
close(pmonitor->m_sendfd);
pmonitor->m_sendfd = -1;
/* Demote the private keys to public keys. */
demote_sensitive_data();
reseed_prngs();
/* Drop privileges */
do_setusercontext(authctxt->pw);
skip:
/* It is safe now to apply the key state */
monitor_apply_keystate(pmonitor);
/*
* Tell the packet layer that authentication was successful, since
* this information is not part of the key state.
*/
packet_set_authenticated();
}
static char *
list_hostkey_types(void)
{
Buffer b;
const char *p;
char *ret;
int i;
Key *key;
buffer_init(&b);
for (i = 0; i < options.num_host_key_files; i++) {
key = sensitive_data.host_keys[i];
if (key == NULL)
key = sensitive_data.host_pubkeys[i];
if (key == NULL)
continue;
/* Check that the key is accepted in HostkeyAlgorithms */
if (match_pattern_list(sshkey_ssh_name(key),
options.hostkeyalgorithms, 0) != 1) {
debug3("%s: %s key not permitted by HostkeyAlgorithms",
__func__, sshkey_ssh_name(key));
continue;
}
switch (key->type) {
case KEY_RSA:
case KEY_DSA:
case KEY_ECDSA:
case KEY_ED25519:
if (buffer_len(&b) > 0)
buffer_append(&b, ",", 1);
p = key_ssh_name(key);
buffer_append(&b, p, strlen(p));
/* for RSA we also support SHA2 signatures */
if (key->type == KEY_RSA) {
p = ",rsa-sha2-512,rsa-sha2-256";
buffer_append(&b, p, strlen(p));
}
break;
}
/* If the private key has a cert peer, then list that too */
key = sensitive_data.host_certificates[i];
if (key == NULL)
continue;
switch (key->type) {
case KEY_RSA_CERT:
case KEY_DSA_CERT:
case KEY_ECDSA_CERT:
case KEY_ED25519_CERT:
if (buffer_len(&b) > 0)
buffer_append(&b, ",", 1);
p = key_ssh_name(key);
buffer_append(&b, p, strlen(p));
break;
}
}
if ((ret = sshbuf_dup_string(&b)) == NULL)
fatal("%s: sshbuf_dup_string failed", __func__);
buffer_free(&b);
debug("list_hostkey_types: %s", ret);
return ret;
}
static Key *
get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
{
int i;
Key *key;
for (i = 0; i < options.num_host_key_files; i++) {
switch (type) {
case KEY_RSA_CERT:
case KEY_DSA_CERT:
case KEY_ECDSA_CERT:
case KEY_ED25519_CERT:
key = sensitive_data.host_certificates[i];
break;
default:
key = sensitive_data.host_keys[i];
if (key == NULL && !need_private)
key = sensitive_data.host_pubkeys[i];
break;
}
if (key != NULL && key->type == type &&
(key->type != KEY_ECDSA || key->ecdsa_nid == nid))
return need_private ?
sensitive_data.host_keys[i] : key;
}
return NULL;
}
Key *
get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
{
return get_hostkey_by_type(type, nid, 0, ssh);
}
Key *
get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
{
return get_hostkey_by_type(type, nid, 1, ssh);
}
Key *
get_hostkey_by_index(int ind)
{
if (ind < 0 || ind >= options.num_host_key_files)
return (NULL);
return (sensitive_data.host_keys[ind]);
}
Key *
get_hostkey_public_by_index(int ind, struct ssh *ssh)
{
if (ind < 0 || ind >= options.num_host_key_files)
return (NULL);
return (sensitive_data.host_pubkeys[ind]);
}
int
get_hostkey_index(Key *key, int compare, struct ssh *ssh)
{
int i;
for (i = 0; i < options.num_host_key_files; i++) {
if (key_is_cert(key)) {
if (key == sensitive_data.host_certificates[i] ||
(compare && sensitive_data.host_certificates[i] &&
sshkey_equal(key,
sensitive_data.host_certificates[i])))
return (i);
} else {
if (key == sensitive_data.host_keys[i] ||
(compare && sensitive_data.host_keys[i] &&
sshkey_equal(key, sensitive_data.host_keys[i])))
return (i);
if (key == sensitive_data.host_pubkeys[i] ||
(compare && sensitive_data.host_pubkeys[i] &&
sshkey_equal(key, sensitive_data.host_pubkeys[i])))
return (i);
}
}
return (-1);
}
/* Inform the client of all hostkeys */
static void
notify_hostkeys(struct ssh *ssh)
{
struct sshbuf *buf;
struct sshkey *key;
int i, nkeys, r;
char *fp;
/* Some clients cannot cope with the hostkeys message, skip those. */
if (datafellows & SSH_BUG_HOSTKEYS)
return;
if ((buf = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new", __func__);
for (i = nkeys = 0; i < options.num_host_key_files; i++) {
key = get_hostkey_public_by_index(i, ssh);
if (key == NULL || key->type == KEY_UNSPEC ||
sshkey_is_cert(key))
continue;
fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT);
debug3("%s: key %d: %s %s", __func__, i,
sshkey_ssh_name(key), fp);
free(fp);
if (nkeys == 0) {
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("hostkeys-00@openssh.com");
packet_put_char(0); /* want-reply */
}
sshbuf_reset(buf);
if ((r = sshkey_putb(key, buf)) != 0)
fatal("%s: couldn't put hostkey %d: %s",
__func__, i, ssh_err(r));
packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
nkeys++;
}
debug3("%s: sent %d hostkeys", __func__, nkeys);
if (nkeys == 0)
fatal("%s: no hostkeys", __func__);
packet_send();
sshbuf_free(buf);
}
/*
* returns 1 if connection should be dropped, 0 otherwise.
* dropping starts at connection #max_startups_begin with a probability
* of (max_startups_rate/100). the probability increases linearly until
* all connections are dropped for startups > max_startups
*/
static int
drop_connection(int startups)
{
int p, r;
if (startups < options.max_startups_begin)
return 0;
if (startups >= options.max_startups)
return 1;
if (options.max_startups_rate == 100)
return 1;
p = 100 - options.max_startups_rate;
p *= startups - options.max_startups_begin;
p /= options.max_startups - options.max_startups_begin;
p += options.max_startups_rate;
r = arc4random_uniform(100);
debug("drop_connection: p %d, r %d", p, r);
return (r < p) ? 1 : 0;
}
static void
usage(void)
{
fprintf(stderr, "%s, %s\n",
SSH_RELEASE,
#ifdef WITH_OPENSSL
SSLeay_version(SSLEAY_VERSION)
#else
"without OpenSSL"
#endif
);
fprintf(stderr,
"usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
" [-E log_file] [-f config_file] [-g login_grace_time]\n"
" [-h host_key_file] [-o option] [-p port] [-u len]\n"
);
exit(1);
}
static void
send_rexec_state(int fd, struct sshbuf *conf)
{
struct sshbuf *m;
int r;
debug3("%s: entering fd = %d config len %zu", __func__, fd,
sshbuf_len(conf));
/*
* Protocol from reexec master to child:
* string configuration
* string rngseed (only if OpenSSL is not self-seeded)
*/
if ((m = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
if ((r = sshbuf_put_stringb(m, conf)) != 0)
fatal("%s: buffer error: %s", __func__, ssh_err(r));
#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
rexec_send_rng_seed(m);
#endif
if (ssh_msg_send(fd, 0, m) == -1)
fatal("%s: ssh_msg_send failed", __func__);
sshbuf_free(m);
debug3("%s: done", __func__);
}
static void
recv_rexec_state(int fd, Buffer *conf)
{
Buffer m;
char *cp;
u_int len;
debug3("%s: entering fd = %d", __func__, fd);
buffer_init(&m);
if (ssh_msg_recv(fd, &m) == -1)
fatal("%s: ssh_msg_recv failed", __func__);
if (buffer_get_char(&m) != 0)
fatal("%s: rexec version mismatch", __func__);
cp = buffer_get_string(&m, &len);
if (conf != NULL)
buffer_append(conf, cp, len);
free(cp);
#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
rexec_recv_rng_seed(&m);
#endif
buffer_free(&m);
debug3("%s: done", __func__);
}
/* Accept a connection from inetd */
static void
server_accept_inetd(int *sock_in, int *sock_out)
{
int fd;
startup_pipe = -1;
if (rexeced_flag) {
close(REEXEC_CONFIG_PASS_FD);
*sock_in = *sock_out = dup(STDIN_FILENO);
if (!debug_flag) {
startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
close(REEXEC_STARTUP_PIPE_FD);
}
} else {
*sock_in = dup(STDIN_FILENO);
*sock_out = dup(STDOUT_FILENO);
}
/*
* We intentionally do not close the descriptors 0, 1, and 2
* as our code for setting the descriptors won't work if
* ttyfd happens to be one of those.
*/